Separation of airborne particles



E. R. UMNEY SEPARATION OF AIRBORNE PARTICLES Dec. 14, 1954 Filed Jan.'7, 1952 I IN YEA/T0,? .LAum fE E. R. UMNE! United States PatentSEPARATION OF AIRBORNE PARTICLES Laurie E. R. Umney, Guildford, England,assignor to Vokes Limited, Guildford, England Application January 7,1952, Serial No. 265,306 Claims priority, application Great BritainJanuary 9, 1951 4 Claims. (Cl. 209-142) According to the invention anairborne stream of 9 particles of varying size is caused to follow anarcuate or curved path through a conduit under the influence of pressurepast an oppositely facing circumferentially disposed lip in the outerwall of the conduit and a relatively small flow of air is inducedthrough a slot past the lip into a recessed pocket in the conduit in thereverse direction to the main flow therein whereby the particles ofsmaller order of size and momentum are decelerated and are deflectedback into the main stream with the small flow while the larger particlesare carried forward past the lip by their greater momentum and fall intoa collector disposed beneath the lip.

In a preferred form of apparatus the main flow of air is sucked throughthe conduit by an extraction fan and the reverse flow of air through theslot is induced through an air inlet in the receptacle by thesame fan.

In operation the larger particles in the main air flow pass through theregion of reverse air flow without being stopped due to their highermomentum and so pass through the slot into the receptacle provided.However the smaller particles which have a lower momentum are arrestedby and become entrained in the reverse air flow and are thus preventedfrom entering the receptacle.

The above and other parts of the invention are embodied in a preferredform of apparatus which will now be described in some detail by way ofexample with reference to the accompanying drawings in which:

Fig. 1 is a sectional view of a separator,

2 is a half sectional view on the line IIII of The curved conduit 1 issquare in cross-section and a suitable dimension is 2 /2 x 2 /2. Theinner circumferential wall 1a at the inlet end has a curvature of 3 /2"radius and the outer wall 1b a curvature of 6" radius over 60, and thenover 75 the walls have curvatures of 9%" and 12 /2 radius respectively,but the outer wall is formed with a recessed pocket 2, deep andextending over 26 of the circumferencefrom a point 90 after theinception of the larger radius of curvature.

Where the pocket 2 ends a slot 3 is defined with the normal continuation1c of the outer wall which'thus constitutes a circumferentially arrangedlip facing the inlet end of the conduit.

Below and behind the lip is arranged an outlet channel 4-5" x 2 /2. Theouter channel has a rubber faced flange 5 for the attachment of areceptacle 6 by means of swinging arms 7 carrying screw bolts 8.

A partition 9 in the receptacle has a narrow horizontal slot 10 for theingress of air through holes 11 in the outer wall 12 on the sideadjacent the conduit outlet.

An extractor fan (not shown) is fitted at the outlet end of the conduit,either directly or at the outlet from an associated dust recovery plantcollecting the finer I particles.

The size and location of the narrow slot in the receptacles areimportant factors effecting the effectiveness of the particle separationwhich are best discovered experimentally for individual installations.

In the apparatus described above the slot 10 is A" deep by 5 /8 long,and its centre is located some 7 /2" below and behind the centre of theslot in the main conduit. The broken line joining the centres of theslots is at an angle of about 35 with the horizontal.

The form of apparatus above described is designed for the extraction ofleaf flakes from mixed tobacco particles in an air stream of C. M. F. ina direction of flow that is from left to right in conduit 1 as regardsthe disclosure of the invention in Fig. 1.

It will be understood that the particular dimensions and arrangements ofthe parts can be widely varied to suit difierent applications andconditions and that such variations are included within the invention inits broader aspects.

For example the suction fan can be replaced by a pressure fan at theinlet end of the conduit and the flow through the gap can be supplied bythis or another pressure fan.

I claim:

1. Apparatus for the separation of particles of a larger order of sizefrom an airborne stream of particles of varying size comprising a curvedconduit through which may be induced a flow of particle laden air, arecessed pocket in the outer circumferetial wall of the conduit, acircumferentially disposed lip defining a slot with the outer wall ofthe pocket, a receptacle for collected particles arranged below and incommunication with the slot, a fan for inducing a relatively small flowof air through the slot and an air inlet in said receptacle for saidfan.

2. Apparatus according to claim 1 in which the re ceptacle is providedwith an air inlet in a wall on the side adjacent the conduit outlet.

3. Apparatus according to claim 1 in which the receptacle is providedwith a double wall on the side adjacent the conduit outlet, an air inletslot in the inner wall and a series of air inlet apertures in the outerwall.

4. Apparatus for the separation of larger particles from an airstreamincluding smaller particles comprising a curved conduit of rectangularcross-section the radius of curvature of which is smaller at its inletend than at its outlet end, a recessed pocket in the outer wall of theconduit, a lip constituted by the outer wall of the conduit beyond therecess and defining a slot with the outer wall of the recess, areceptacle arranged below the slot, an air inlet in a wall of thereceptacle on the side adjacent the conduit outlet, and means to inducean air flow through the conduit and through the slot.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 821,819 Neumann May 29, 1906 1,023,750 Morscher Apr. 16, 19121,264,023 Davis Apr. 23, 1918 2,044,915 Mosely June 23, 1936 2,283,483Arnold May 19, 1942 FOREIGN PATENTS Number Country Date 120,673 SwedenNov. 20, 1947 483,307 Germany Sept. 28, 1929

